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49 records · Page 3Linked to original sources
PubMed1990

Leptopilina heterotoma and L. boulardi: strategies to avoid cellular defense responses of Drosophila melanogaster.

Eggs of three strains of the cynipid parasitoid Leptopilina heterotoma and a Tunisian strain (G317) of L. boulardi are not encapsulated by hemocytes of Drosophila melanogaster hosts, but the eggs of a Congolese strain (L104) of L. boulardi are encapsulated. To determine the reason for the difference in host response against the parasitoid eggs, lamellocytes (hemocytes that encapsulate foreign objects and form capsules around endogenous tissues in melanotic tumor mutants) were examined in host larvae parasitized by the five Leptopilina strains. Parasitization by the three L. heterotoma strains affected the morphology of host lamellocytes and suppressed endogenous melanotic capsule formation in melanotic tumor hosts. L104 did not alter the morphology of host lamellocytes nor block tumor formation in melanotic tumor mutant hosts. The morphology of some lamellocytes was affected by G317 parasitization but host lamellocytes were still capable of forming melanotic tumors and encapsulating dead supernumerary parasitoid larvae. Therefore, the eggs of strains affecting lamellocyte morphology are protected from encapsulation by the host's blood cells. L. heterotoma eggs float freely in the host hemocoel but L. boulardi eggs are attached to host tissue surfaces. Lamellocytes cannot infiltrate the attachment site so the capsule around the L104 egg remains incomplete. The wasp larva uses this gap in the capsule as an escape hatch for emergence.

Animals↗
PubMed1992

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.

Animals↗
PubMed1985

Encapsulation ability of Drosophila melanogaster: a genetic analysis.

Insects are able to effectively recognize parasitoid eggs or larvae and to eliminate them by formation of a hemocytic capsule. Although the cellular process is now well documented, the genetic aspects of recognition of foreignness and the encapsulation process are still poorly understood. Experiments using the isofemale-strain method showed that the encapsulating ability of Drosophila melanogaster exercised against a parasitic wasp varies within a given population and that this variability is under partial genetic control.

Animals↗
PubMed1991

Pupal parasitoids (Hymenoptera: Pteromalidae) of muscoid filth flies in Israel.

Pupal parasitoids of muscoid flies were collected monthly on three farms in southern Israel in preparation for an IPM programme for the control of filth-breeding flies. 50% and 25.5% of viable puparia collected during 1985 and 1986/87, respectively, were parasitized. Three species of Spalangia Latreille and two species of Muscidifurax Girault & Saunders (Hymenoptera: Pteromalidae) accounted for 82.0% and 94.2% of parasitoids recovered in the two seasons. Variation in the seasonal abundance and distribution of the leading parasite species are discussed in connection with their conservation and possible use for augmentative releases within IPM projects.

Animals↗
PubMed1991

Life history of Spalangia gemina Boucek (Hymenoptera: Pteromalidae), a fast-breeding microhymenopteran pupal parasitoid of muscoid flies.

Laboratory studies at 25.5 degrees C and 70-75% r.h. demonstrated that the average daily survival rate for females of the parasitoid Spalangia gemina Boucek (Hymenoptera: Pteromalidae) was 0.907 over a 20-day period, with 50% mortality in 17.3 days. Mean immature developmental time of S.gemina was 22 days and the population growth rate was c. 40-fold per generation. The females successfully parasitized 1-, 2- and 3-day-old pupae of Musca domestica L. and parasitism of 98-100% was obtained at parasitoid to host ratios of 1:0.5-2.5. Parasitism of 81-87% was obtained at parasitoid to host ratios of 1:10. The male to female sex ratio was 1:1.59. S.gemina appears to have advantages over other Spalangia spp., which have immature development times of 28-32 days under comparable conditions, for the biological control of Muscidae.

Age Factors↗
PubMed1990

Evidence for chromosomal transmission of polydnavirus DNA.

Heterogeneity in polydnavirus DNA was exploited as a means of following the transmission of viral genomes in parasitoid populations. Parasitoid lines isogenic for viral DNA markers were established from both a braconid (Cotesia melanoscela) and an ichneumonid (Hyposoter fugitivus) species. In crossing experiments these markers routinely segregated in Mendelian (chromosomal) fashion, suggesting that the structure of polydnavirus genomes is probably determined by the integrated form of viral DNA, rather than by extrachromosomal molecules.

Animals↗
PubMed1991

Stimulation of embryonic development in Microplitis croceipes (Braconidae) in cell culture media preconditioned with a fat body cell line derived from a nonpermissive host, gypsy moth, Lymantria dispar.

A cell culture medium, IPL-52B, was preconditioned with host fat body and two insect cell lines to determine if they would support embryonic development of Microplitis croceipes in vitro. The medium was preconditioned with the cell line IPL-LdFB, derived from fat body of the gypsy moth, Lymantria dispar, cell line IAL-TND1, derived from imaginal discs of the cabbage looper, Trichoplusia ni, and whole fat body tissue from host Helicoverpa zea. A second cell culture medium, Excell 400, was preconditioned with only the cell line, IPL-LdFB. Pregerm band eggs were dissected from third instar host larvae and incubated in the conditioned medium for 20 h. Newly laid parasitoid eggs did not develop in unconditioned IPL-52B, but did develop to germ band stage in unconditioned Excell 400. The IPL-52B medium conditioned with both cell lines induced germ band formation, but only the L. dispar cell line (IPL-LdFB) promoted significant development to eclosion comparable to host far body tissue. Excell 400 medium preconditioned with the cell line, IPL-LdFB also supported development to eclosion.

Animals↗
PubMed1979

An insect glycoprotein: a study of the particles responsible for the resistance of a parasitoid's egg to the defence reactions of its insect host.

A study has been carried out of the chemical composition and physical structure of small particles, 130 nm in diameter, isolated from the calyx of the ichneumon, Nemeritis canescens. The particles are vesicular, consisting of a densely-staining core surrounded by an outer membrane. The core of the particles is made up of protein and carbohydrate in the ratio 100:17; no nucleic acid was detected. The basic chemical subunit of the core of the particles appears to be a glycoprotein of molecular mass ca. 45 000. The basic structural subunit of the core, however, is a short, hollow cylinder, about 10 nm across. It seems likely that several chemical subunits make up one structural subunit, and that many structural subunits, surrounded by the membrane, make up a single particle.

Amino Acids↗
PubMed1992

Genetic determinism of the cellular immune reaction in Drosophila melanogaster.

Larvae of Drosophila melanogaster produce a haemocytic reaction against eggs of the parasitoid Leptopilina boulardi, which leads to the formation of a multicellular capsule surrounding the foreign object. Melanization resulting from the conversion of phenol to o-quinones frequently accompanies the cellular reaction. Although various cytological and biochemical aspects of this reaction have been investigated, very little is known about genetic determinism of the insect immune response. The heredity of the capacity to encapsulate was analysed by comparing 16 reciprocal crosses made using inbred resistant and susceptible parental strains. We conclude that differences in the encapsulation capacity of D. melanogaster are inherited autosomally, with the reactive phenotype showing complete dominance over the non-reactive one. There were neither sex-linked nor maternal effects. The results of all crosses suggest a single major segregating locus with two alleles and complete dominance of the resistant allele, with cytoplasmic factors and minor modifying genes acting on the major locus.

Animals↗
PubMed1989

Influence of habitat and temperature on dispersal behaviour of two pteromalid parasitoids of houseflies during an inundative release at a dairy barn.

1. About 11,000 each of Muscidifurax raptor Girault and Saunders and Urolepis rufipes (Ashmead) were released weekly for 7 weeks at a commercial dairy farm in central New York state, U.S.A. Dispersal behaviour was monitored by parasitism rates of house fly, Musca domestica L., pupae placed in sentinel bags. 2. M. raptor, which was released inside the barn, parasitized fly pupae both inside and outside, and it achieved highest rates of parasitism in indoor straw calf-bedding and in outdoor manure and silage. 3. U. rufipes, which was released outside the barn, did not attack pupae inside the barn, and its highest rates of parasitism occurred in outdoor manure and silage. 4. M. raptor appeared to be more effective than U. rufipes in parasitizing pupae located at sites where natural fly-breeding occurred. 5. Interspecific competition did not appear to explain these distribution patterns. 6. There was no significant trend in parasitism by M. raptor as a function of distance from the release station. Furthermore, high rates of parasitism near open doorways and at an outdoor site 30 m away suggests that M. raptor dispersed throughout the barn and its immediate surroundings. 7. Air temperature was positively correlated to flight activity, but not to parasitization activity in natural fly-breeding substrates.

Animals↗
PubMed1988

Interference with function of plasmatocytes of Heliothis virescens in vivo by calyx fluid of the parasitoid Campoletis sonorensis.

Immature stages of the ichneumonid parasitoid, Campoletis sonorensis, develop within the haemocoel of its noctuid host, Heliothis virescens. The host cannot encapsulate the parasitoid egg owing to the suppressive effect of the polydnavirus-laden calyx fluid injected by the female parasitoid during oviposition. We have examined the effects of injection of calyx fluid on the following haemocytic manifestations of the immune system of 5th-instar larvae of H. virescens: encapsulation, nodulation, phagocytosis, erythrocyte rosetting and coagulation. Of these phenomena, only those requiring the formation of a multicellular sheath of plasmatocytes were affected. In general, encapsulation was fully suppressed; all of the C. sonorensis eggs and most of the glass rods implanted as targets were devoid of attached haemocytes 3 days after implantation although a few of the latter were coated by a sparsely distributed layer of granulocytes. Plasmatocytes also appeared to be present in thicker depositions of haemocytes. In nodulation, only the second, encapsulation-like phase was inhibited. The resistant first stage, involving the entrapment of particles by haemocytes, only resulted in the formation of amorphous, disorganized nodules. Granulocyte-dependent aspects of the immune system (phagocytosis, rosetting and possibly coagulation and the first stage of encapsulation and nodulation) occurred normally. The data suggest that in 5th-instar hosts injection of calyx fluid acts specifically on plasmatocyte function.

Animals↗